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LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
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4.8 USB Troubleshooting
USB Initial sequence of CU405 is :
USB connected to CU405 power on
→
USB_VBUS(Q500) go to 5V
→
USB_D+ go to 3.3V
→
48M Crystal on
→
USB_VP and USB_VN is triggered
→
USB work.
Start
Q500 4 pin is 5V?
USB_D+ is 3.3V?
48M clock is running?
Change the Main board
Check Q500
Check U401
Check X200
NO
YES
YES
YES
NO
NO
Cable is inserted?
YES
Insert cable
NO
Power is on?
YES
Go to power on trouble shooting
NO
Summary of Contents for CU405
Page 1: ...Date May 2007 Issue 1 0 Service Manual Model CU405 Service Manual CU405 Internal Use Only ...
Page 175: ...Note ...
Page 176: ...Note ...